The present invention relates to a disk cartridge in which a double-sided disk is housed and, more particularly, to a shutter member for opening and closing head entry apertures formed in at least both surfaces of the disk cartridge.
To make it easy to handle and protect it from dust, a recording medium in the form of a disk, such as a magnetic disk or optical disk, which can record and reproduce desired information is still held in a disk cartridge even when it is loaded into a recording and reproduction apparatus. Therefore, a cartridge case which forms the main body of the disk cartridge is provided with a head entry aperture which enables a head to access the disk recording medium when the cartridge is loaded into the recording and reproduction apparatus. However, the provision of a head entry aperture in this manner presents some disadvantages. For example, when the disk cartridge is not being used, dust can enter the cartridge case through this head entry aperture and adhere to the recording surface of the disk recording medium. When the disk cartridge is being handled, fingers, etc., can touch the recording surface of the disk cartridge through the head entry aperture, and dirty or scratch this surface. Therefore, the provision of such a head entry aperture could damage the recording or reproducing performance. For this reason, a disk cartridge is usually provided with a shutter which closes the head entry aperture when the disk is not being used.
FIGS. 12a and 12b are plan views of an example of a conventional disk cartridge of this type (such as that disclosed in Japanese Utility Model Unexamined Publication No. 38388/19-82), in which FIG. 12a shows the front side and FIG. 12b shows the reverse side. As shown in FIGS. 12a and 12b, a cartridge casing 1 has, an upper casing 2, a lower casing 3, a recording medium 4 in the form of a disk, spindle holes 5A and 5B, head entry apertures 6A and 6B, a shutter 7, shutter surfaces 7A and 7B, and openings 8A and 8B.
As shown in FIGS. 12a and 12b, the cartridge casing 1 is integrally formed of the upper casing 2 and the lower casing 3, and incorporates the disk recording medium 4, of which both surfaces can be used. The spindle holes 5 have the same diameter and are coaxially formed in the upper and lower casings 2 and 3. The head entry apertures 6A and 6B have the same shape and are formed at positions between the front end of the casing and the spindle holes 5 of the upper and lower casing 2 and 3 (top of the figures) in such a manner that they cross the entire recording area of the disk recording medium 4 in the radial direction thereof and coincide with each other in the direction perpendicular to the recording surfaces.
The shutter 7 has a U-shaped profile and is attached to the cartridge casing 1 in such a manner that the cartridge casing is sandwiched between the two sides of the shutter. The opening 8A is formed in the shutter surface 7A of the shutter 7 on the side of the upper casing 2 in a position which is shifted from the center of the shutter surface 7A to the right as viewed in FIG. 12a. The opening 8B is formed in the shutter surface 7B of the shutter 7 on the side of the lower casing 3 in a position which is shifted from the center of the shutter surface 7B to the left as viewed in FIG. 12b. The positions of the openings 8A and 8B coincide with each other in the direction perpendicular to the recording surfaces. The shape of the openings 8A and 8B is generally the same as that of the head entry apertures 6A and 6B, but their size is slightly greater than that of the apertures 6A and 6B.
The shutter 7 can slide relative to the cartridge casing 1 in the directions indicated by the arrows A and B.
When the disk cartridge is not being used, the shutter 7 is positioned at one end of its slidable range, as shown in the figures, so that the head entry apertures 6A and 6B are closed. However, when the disk cartridge is being used, the shutter 7 is moved in the direction indicated by the arrow A until it is positioned at the other end of the slidable range. The opening 8A of the shutter 7 is thereby set in a position at which it surrounds the head entry aperture 6A of the upper casing 2, and the opening 8B is set in a position at which it surrounds the head entry aperture 6B of the lower casing 3, thereby exposing the head entry apertures 6A and 6B. The disk cartridge 1 is thereafter moved, so that the head can be brought into contact with one of the two recording surfaces of the disk recording medium 4 through the corresponding head entry aperture 6A or 6B and, at the same time, a pad can be brought into contact with the other recording surface through the other head entry aperture. A spindle is inserted through the spindle hole 5A or 5B, and a center hub of the disk recording medium 4 is engaged with the spindle. When the disk cartridge 1 is removed from the recording and reproduction apparatus, the head entry apertures 6A and 6B can be closed by the movement of the shutter 7 in the direction indicated by the arrow B.
In the disk cartridge thus constructed, the shutter 7 is adapted to be moved relative to the cartridge casing 1 only in the direction indicated by the arrow A in order to open the head entry apertures 6A and 6B. Therefore, if the disk cartridge is used with the upper casing 2 shown in FIG. 12a facing upward to record or reproduce information by using one of the recording surfaces of the disk recording medium 4, the shutter 7 must be moved in the direction indicated by the arrow A in order to open the head entry aperture 6A, because the shutter had been resting at the right end of the slidable range. Conversely, if the recording or reproduction of information is performed by using the other recording surface of the disk recording medium 4, the disk cartridge is inverted relative to the state shown in FIG. 12a in which the lower casing 3 faces upward, with the shutter 7 resting at the left end of the slidable range, as shown in FIG. 12b. The shutter 7 must be moved in the direction indicated by the arrow A in FIG. 12b in order to open the head entry aperture 6B, but, in this case, the direction indicated by the arrow A in FIG. 12b is opposite to the direction indicated by the arrow A in FIG. 12a with respect to the recording and reproduction apparatus.
As can be understood from the foregoing, this type of cartridge necessitates two sets of shutter moving mechanisms, resulting in a complicated structure of the recording and reproduction apparatus, since the direction of movement of the shutter 7 in the recording and reproduction apparatus must be changed depending upon which recording surface of the disk recording medium 4 is used to record or reproduce information.
To cope with this problem, the applicants proposed, in Japanese Patent Laid-Open No. 43279/1985, a disk cartridge in which it is sufficient to move the shutter in only one direction in order to open the head entry apertures in a recording and reproduction apparatus, irrespective of which side of the recording surfaces of the disk recording medium is to be used to record or reproduce information.
FIGS. 13a and 13b are plan views of this disk cartridge, in which FIG. 13a shows the front side and FIG. 13b shows the reverse side. Parts corresponding to those shown in FIGS. 12a and 12b are given the same reference symbols.
The shutter 7 of this disk cartridge has a U-shaped profile and is attached so as to sandwich the cartridge casing 1. However, there is no opening in either of the shutter surface 7A or the shutter surface 7B, and these shutter surfaces are rectangular and large enough to sufficiently cover the head entry apertures 6A and 6B the spindle holes 5A and 5b. This shutter 7 can slide along a guide grooves 9A and 9B which are formed in the upper and lower casings 2 and 3, respectively, of the cartridge casing 1. When the disk cartridge is not being used, the shutter 7 is in a position corresponding to the center of the cartridge casing 1 in the widthwise direction, and is urged by spring members 10A and 10B so that the spindle holes 5A and 5B and the head entry aperture 10A and 10B are all closed thereby.
When one of the two recording surfaces of the disk recording medium 4 is to be used to record or reproduce information by setting the disk cartridge so that the upper casing 2 in FIG. 13a faces upward, the shutter 7 is moved against the urging force of the spring member 10B by a shutter moving mechanism (not shown) in the direction indicated by the arrow A as far as the end of the slidable range. The spindle hole 5A and the head opening aperture 6A are thereby exposed. At the same time, on the reverse side of the disk cartridge shown in FIG. 13b (i.e., on the side of the lower casing 3), the shutter 7 moves relative to the lower casing 3 in the direction indicated by the arrow B, so that the spindle hole 5B and the head entry aperture 6B are also exposed.
When the other recording surface of the disk recording medium 4 is used to record or reproduce information, the disk cartridge is set so that the lower case 3 faces upward, as shown in FIG. 13b. In this case, the spindle hole 5B and the head entry aperture 6B are exposed by moving the shutter 7 against the urging force of the spring 10A (FIG. 13a) in the direction indicated by the arrow A (in the same direction as that indicated by the arrow a in FIG. 13a relative to the recording and reproduction apparatus). At the same time, on the front surface side of the disk cartridge (i.e., the side of the upper casing 2), the shutter 7 moves relative to the upper casing 2 in the direction indicated by the arrow B, so that the spindle hole 5A and the head entry aperture 6A are also exposed.
In this disk cartridge, it is sufficient to move the shutter 7 in the same direction irrespective of which recording surface of the disk recording medium 4 is used to record or produce information. Therefore, the shutter moving mechanism can be simplified, resulting in a simpler construction of the recording and reproduction apparatus. In addition, dust-proofing effect can be provided for the spindle holes 5A and 5B.
When the above-described disk cartridge proposed by the applicants is used, it is necessary to move the shutter located at the center of the slidable range up to the end thereof in order to open the spindle holes and head entry apertures. Therefore, the shutter moving mechanism is disposed on a straight line which connects the spindle hole 5A or 5B to the head entry aperture 6A or 6B. It should be noted here that a carriage mechanism for moving the head and pad, etc., is also installed on this straight line. It is therefore very difficult to determine the disposition of the shutter moving mechanism. Moreover, the construction of this mechanism tends to be complicated and bulky.